This essay critically reviews the opposition between believing in a rational way and believing in an emotional way, believing with reason or with the heart. Its objective is not to determine which way of believing has to be considered as being of a higher quality than the other. It rather wants to analyse the public discourse in which religion is opposed to spirituality, where the latter is considered to be a matter of the heart and of emotion. The heart is then seen as superior to reason, as it also is in evangelical and charismatic circles. As a matter of fact, reason and heart are metaphors in the public discourse on religion and spirituality, and both metaphors refer to a certain subsystem of cognition, the implicative (heart) and the propositional (reason). Both subsystems of cognition are at work in the practice of religion and spirituality. They can be compared to the traditional distinction between fides quae and fides qua. Religion needs both, as a bird needs two wings to be able to fly.